Near field communications (NFC)-RFID is incorporated in a number of modern day devices. Two of the most common uses of NFC-RFID technology are within credit cards and personal identification badges. When a given credit card is passed close to a corresponding reader, a credit card transaction is processed. Similarly, when a personal identification badge is passed close to a corresponding reader, an unattended entrance gate, or turnstile, permits admission.
RFID involves the hardware known as readers (also known as interrogators), and transponders (also known as tags or labels), as well as RFID software or RFID middleware. Inductively coupled NFC-RFID systems are based on a transformer-type coupling between a primary coil in a reader and a secondary coil in a transponder. Typically, coupling occurs when the distance between the corresponding coils is within approximately 0.16 ft., such that the transponder is located in the near field of the reader's antenna. Electrical energy is transmitted from the reader to the transponder via magnetic coupling between the primary coil in the reader and the secondary coil in the transponder.
RFID can be either passive (using no battery), active (i.e. the transponder has an on-board battery and broadcasts or beacons a signal) or battery assisted passive (BAP) which incorporates a small battery on board that is activated when a transponder is proximate a reader. Some RFID transponders are read from several meters away and beyond the line of sight of the reader. NFC-RFID is related to systems that rely on a transponder being in close proximity to a corresponding reader. When a resonant transponder is placed within the magnetic alternating field of the reader's antenna (i.e. the self-resonant frequency of the transponder corresponds with the transmission frequency of the reader), the transponder draws energy from the magnetic field generated by the reader. This additional power consumption can be measured as voltage drop at the internal resistance in the reader's antenna through the supply current to the reader's antenna. Switching on and off of a load resistance at the transponder's antenna therefore effects voltage changes at the reader's antenna and thus has the effect of an amplitude modulation of the antenna voltage by the remote transponder. When switching on and off of the load resistor is controlled by data, this data can be transferred from the transponder to the reader. This type of data transfer is called load modulation. To reclaim the data in the reader, the voltage measured at the reader's antenna is rectified. This represents the demodulation of an amplitude modulated signal.
Concurrent with the evolution of RFID technology, use of digital field devices in modern manufacturing and processing plants is becoming quite common. Often times, a digital field device forms an integral portion of a given asset. The term “integral” is used herein to mean that the element (i.e. digital field device) is intended to remain fixed to, and remain with a given asset, wherever the given asset may be moved. Assets that are considered to be “repairable” parts are generally more expensive assets that are often times taken out of service, rebuilt and subsequently either stored in a plant warehouse for later use or returned to service. Any given asset may be returned to service in a different area of a plant or placed in service in a different plant all together.
It has become desirable to provide storage of, and access to, corresponding original asset data, asset configuration data, asset historical operations data and asset historical maintenance data that remains with, and forms an integral part of, high value plant assets. It is equally desirable to provide access to, and interaction with, real time asset operating data and diagnostics information. Having access to the asset data even when the given asset is out of service is particularly desirable.